If you want to use TokuDB with MariaDB, MySQL, or Percona Server, you will need to disable support for transparent hugepages in Linux.

Fortunately, this is very easy to check, and to change.

An easy way to check is with:

cat /sys/kernel/mm/transparent_hugepage/enabled

This will return something like:

[always] madvise never

Note the word surrounded by “[]” is what this option is set to. So the above is set to “always”. To disable it, we want it set to “never”.

I’ve found the easiest way to change/set this is to add the below to your /etc/rc.local file (and then reboot your system):

if test -f /sys/kernel/mm/transparent_hugepage/enabled; then
   echo never > /sys/kernel/mm/transparent_hugepage/enabled
fi
if test -f /sys/kernel/mm/transparent_hugepage/defrag; then
   echo …

TokuDB is gaining more and more popularity and many people are finding it very helpful for certain cases.

Using/enabling it in some distributions can be quite a pain, but enabling it in MariaDB is easy as 1-2-…, well, only 1-2, since that’s all there is to it!

1. Ensure you have the correct MariaDB version:

• MariaDB 5.5.36+
• MariaDB 10.0.9+
• Note: Linux 64-bit systems only – specific packages include: Ubuntu, Debian, Fedora, CentOS, Red Hat
• Note: If using the Linux tarball – it must be the version built with glibc 2.14+

2. Run this command:

INSTALL SONAME 'ha_tokudb';

or update my.cnf file with:

[mysqld]
plugin-load=ha_tokudb

There is one requirement from TokuDB, which is to have transparent …

If you try to install the TokuDB storage engine on a modern Linux distribution it might fail with following error message:

2014-07-17 19:02:55 13865 [ERROR] TokuDB will not run with transparent huge pages enabled.
2014-07-17 19:02:55 13865 [ERROR] Please disable them to continue.
2014-07-17 19:02:55 13865 [ERROR] (echo never > /sys/kernel/mm/transparent_hugepage/enabled)

You might be curious why TokuDB refuses to start with Transparent HugePages. Are they not a good thing… allowing smaller kernel page tables and less TLB misses when accessing data in the buffer pool? I was curious, so I asked Tim Callaghan this very question.

This problem originates with TokuDB using jemalloc memory allocator, which uses a particular trick to deal with memory fragmentation. The classical problem with memory allocators is fragmentation – if you allocated a say 2MB chunk from the operating system (typically using …